Apparatus for placing seismic explosive charges



Dec. 11, 1956 J. NORMAN, JR, ETAL 2,773,669

APPARATUS FOR PLACING SEISMIC EXPLOSIVE CHARGES Filed Oct. '29, 1953 Fig. 1

2 Sheets-Sheet 1 INVENTORS Joe Norman Jr.

A. B. Hamil ATTORNEY Dec. 11, 1956 J. NORMAN, JR., EIAL 2,773,669

APPARATUS FOR PLACING SEISMIC EXPLOSIVE CHARGES Filed on. 29-, 1953 2 Sheets-Sheet 2 F 5 H9. 4 lg 'INVENTORS Jae N0rman,J1:

A. B. Hamil Arromvfr United States Patent APPARATUS FOR PLACING SEISMIC EXPLOSIVE CHARGES Joe Norman, Jr., and A. B. Hamil, Houston, Tex. Application October 29, 1953, Serial No. 389,106

6 Claims. (Cl. 255-1) This invention pertains to apparatus for placing subsurface explosive charges in connection with seismic exploration such as is conducted in prospecting for oil.

If a hole is drilled in mushy or sandy soil, the hole will close up as soon as the drill pipe is removed. It is therefore necessary to leave the drill pipe in the hole as a casing to prevent such collapse of the walls. This is equally true whether the hole is for producing oil or for reception of an explosive charge used in seismographic exploration. However in seismographic work the pipe left in the hole after the charge has been exploded is a pure waste, there being no further need for the hole after the charge has been exploded and the seismograph record made.

The drill pipe if left in the hole as a casing must have a diameter the same size as the desired hole. This means that either the drill pipe must have as large a diameter as the bit, causing considerable friction during drilling, or the bit must be bigger than the desired hole. It costs too much to drill a hole larger than necessary, so the hole is made the same diameter as the pipe. But with the pipe tight in the hole it costs more to pull it out after the charge has been exploded than the pipe is worth. Even if an oversize hole were drilled the pipe would probably be tight in the hole after the charge was exploded.

According to the invention casing is saved by drilling the hole with the explosive charge disposed adjacent the drill bit, instead of lowering it in after the hole has been drilled. Since the charge is then already at the bottom of the hole, the drill pipe above need not be as large in diameter as the bit and is therefore not tight in the hole. This makes it easier to drill the hole and after the hole is drilled the pipe can be disconnected from the bit and easily pulled to the surface.

The ignition cable which must extend from the charge to the surface is placed in the lower end of the drill pipe in the form of a spool, one end being connected to the charge in the drill bit and the other fixed to the spool. Then as the hole is drilled the cable as well as the charge is always at the bottom of the hole. After the hole is drilled to the desired depth, the drill pipe is disconnected from the drill bit and charge and, as the pipe is withdrawn, the spool unwinds and the cable is left in the hole, extending from top to bottom.

For a description of a preferred embodiment of apparatus useful in carrying out the method of the invention, reference will now be made to the accompanying drawings in which:

Figure 1 is a front elevation, largely in section, showing a charge placing apparatus according to the invention;

Figure 2 is a side elevation of a portion of the apparatus shown in Figure 1;

Figure 3 is a horizontal section taken on the plane 33 of Figure 1;

Figure 4 is a vertical section showing the apparatus of ;.--Figure 1 disposed in a hole in the earths surface, with the bit detached, the drill pipe raised, and the cable parztlially unwound; and

Figure 5 is a vertical section similar to Figure 4 but showing the drill pipe completely removed and the cable connected to an electric generator at the surface.

Referring to Figure 1, there is shown a drill bit 10 having holes or nozzles 10a through which water is projected under pressure during the drilling operation. A length of pipe 11 is screwed into the drill bit. A tubular explosive receptacle 12 is disposed inside the pipe 11 and held in place by struts such as 13, 14 (see also Figure 3). The receptacle is filled with explosive not shown. A detonator cap 15 isimbedded in the explosive and thereby insulated against mechanical shocks during drilling. -A stopper 16 closes the top of the receptacle for explosive. There is a hole 17 in the stopper through which passes ignition cable 18 which is connected at one end to cap 15.

A .pipe 19 is connected to pipe 11 by means of a releasable fastening such as a double bayonet joint, illustrated in Figs. 1 and 2 as comprising radially extending pins 19a on the pipe 11 which are slidable within L-slots 19b in the pipe 19. A ring 20 is secured to pipe 19 inside thereof. An 0 ring 21 of neoprene or other rubberlike material is frictionally held in a groove in the lower face of ring 20 and makes contact with the upper end of pipe 11 to form a liquid tight seal between the two pipes and provide a certain amount of frictional resistance to uncoupling of the bayonet joint. 7

A tubular housing 22 telescopes over the top of receptacle 12 to the extent permitted by stop ring 23 fastened inside housing 22 a short distance from its lower end. The upper end of thehousing is closed by a cone shaped plug 22a fastened thereto. A spool 24 is screwed into plug 22a. Ignition cable or wire 18 is wound on spool 24- and the upper end of this cable is fastened to the spool. A pair of spring fingers 25, 26 are fastened at their upper ends to the side of housing 22, the lower ends of the fingers tending to expand and press outwardly on pipe 19. In the position shown in Figure l the fingers serve to position the housing 22 inside pipe 19.

In order to insure that the housing 22 cannot completely separate from the pipe 19, when the pipe 19 is raised as hereinafter described, we provide a safety means comprising a line 27 which is attached at one end to an engaging ring 28 on the top of plug 22a by means of a releasable snap coupling 29. Inside a pipe 30, which is screwed to the top of pipe 19, is secured a bar 31 to which a swivel 32 on the upper end of line 27 is fastened. If for any reason, therefore, the fingers 25, 26 should drop past the rings 20, 21 inside of pipe 19, the housing 22 will be suspended within pipe 19 by means of the line 27. The upper end of the pipe 30 is reduced and is screwed to the drill pipe 33 to complete the'drill string.

In assembling the apparatus the housing 22 is placed on top of receptacle 12. Then pipe 19 is placed over the top of the housing, whereby spring fingers 25, 26 first are forced inwardly by rings 20 and 21 to a retracted position and then are permitted to snap outwardly to engage the inner surface of pipe 19. In using the apparatus, water can be circulated down through the drill pipe, out through the holes 10a in the drill bit 10 and back to the surface as usual. The spool housing and explosive receptacle keep the cable and .chargedry and, of course;

prevent the dynamite charge from being washed away by the circulating water. After the hole has been drilled deep enough pipe 19 is uncoupled from pipe 11 and the drill pipe 33 is raised carrying pipes 30 and 19 with it. Spool housing 22 drops down until the spring fingers 25, 26 engage ring 21 whereupon the cable 18 begins to unwind as shown in Figure 4. Should the fingers fail to hold, the spool will be retained by line 27 though it will then be below pipe 19. On reaching the surface the cable is cut from the spool and connected to generator 34 as shown in 'FigureS. The spool can be removed through thetop of pipe '19 "after "unscrewingpipe 30. The'drill bit and explosive receptaclerand pipe 11 will be destroyed 'by the explosion of the charge butthis lOSs will be .neg-

'li'g'ible since an inexpensive bit "is used for drilling the 'shallow*'sei'stnic"charge"hdles. The drillpipe'and' thesp'ool housing an'd'pipes'1'9 andfi'O willbesaved.

The apparatusdescribedcan=be'considerablywaried to carry 'outthe method under varyingconditions. "Various parts *shown as "separable 'can be made 'integral'and vice versa. Thus, f pipes 30 can be integral 'with the lower length-ofdrill'pipe Pipe 30"can also be integralwith pipe 19 and,to"facilitate-removal of *the spool housing, thespring fingers "can be reversed 'to'point upwards and be provided with "hooks to engage a'rin'g "like "ring 20 disposed-'abovethe level 'of the housing. A tube could then beipla'ced'over theloweren'd of the housing to compress the fingers to "permit withdrawal of the housing. The spool can'be revolvably 'mounted and can "be made with'either'a -horizontalor vertical-axis. A coneshaped spool cou'ld beused to'fa'cilitate unwinding. Pipe'19'can fitins'ide as wlhasodts'idepipe 11. A quick make'up screw 'connection of the low reverse torque type 'known as a safety 'joint "could he-substituted for the bayonet jointyoras'imple telescopingjointwith a friction fitand with some non-circular section, e.-'g.,*hexagonal'to'transmit rotationcould be used; or a releasable coupling actuated hydraulically or mechanically from the surface might "be desirable insome cases. 'The pipe '11 and -receptar'zle '12 can be made in short sections fitted "together :in any desired manner, 'su'fii'cient sections "being "used to accommoda-te the size=of'explosive'chargerequired. 'The'spool housing for theexplosivereceptacle can be "eccentrically located, -*e. g. againstone "side ofthe pipes therearound, instead of concentric therewith. 'The bit IQ-and pipe 11 can be made integral. 'But regardless of the details 'of the apparatus used, the general'methodremains the "same. ByJnean's of the method the charge placed in the hole may be of alargersizethan couldbe lowered through the dr'ill pipe'in accordance with prior-practice.

While a preferred embodiment ofthe 'apparatus-o'fthe invention has been illustratedand-described 'and as several variations thereof have been described and 'a preferred procedure for carrying I out the "method 'of the invention has been "described, it is'obvious that*many*rnodifications of "the invention *can be made "by one'skilledin the art without -"departing from "the spirit of the invention and it is intended toprotect by Letters :Patent all formsof'the invention falling within the scopeof the following claims.

' 1. :Apparatus for plac ingean explosive 'charg'ebeneath the e'arth ssurfacecomprisinga"drillpipe,a drill bit, said drill bit having 'an 'explos'ive charge connected thereto, *a quantity of'ignition cablezdisposedadiacent the lower end of I the 1 drill bit, means connecting'one end of thecable to the lower end: dfithe 'drill'pipe, means connecting the other end of the-"cable to the'eXpIOsive charge, hous'ing means enclosing said cable and said explosive charge, and releasable means connecting saiddrill pipe to said =drill"bit.

2: 11:1 combination, afirst "pipe, a'tubu'lar receptacle'of smaller cross sectional area *than ithe pipe disposed inside the pi'pe and secured .thereto, said receptacle being 'closed atfitsilower end and open a't its =top end, aclosure for the upper en'd'cof the receptacle, can sclosure having 'a hole therethrough, iazsecond pipe, asecond tubdlar housing *insidefihesecondpip'e and releasably secured thereto, "a

spool disposed in said housing, an ignition cable wound on the spool and connected thereto at one end, the other end of said cable passing through said hole in said closure for the receptacle, a detonator on said other end of the cable, an explosive charge in.said receptacle, said detonator being buried in said charge, and releasable means coupling the upper :iend of f the fiIStlpiPeIO the slower end of the second pipe.

3. In combination, a-first pipe having .an.upp.er end of reduced diameter anda'lower end of -larger diameter, a second pipe of the same diameter as the lower "end of the first pipe, means releasably connecting the top of the second pipe to the bottom of the "first pipe, a ring secured in the lower end of the second pipe, a cylindrical housing inside of and concentric with the second pipe, said housing having a closed top and an iopen-bottom, said housing having a smaller outer diameter than Ithe inside. diameter o'f the second pipe leaving an annular space"therbetween, a plurality of springi fin'gers secured at theiriupper ends tosaidhousing and'having their lower ends pressing 'againsttheiinside o'fthesecon'd pipe above said. ring, aspoolidisposed in saidhous'ing withits axis vertical and :its uppenend secured to "the top of said housing, a secondxing secured inthe lower .part of said housing spaced from the lower end thereof, a third pipe, a'bayo'netj'oint couplingthe top of the third pipetothe bottomof'the secundp ip'e, a cylindrical receptacle in the third pipe and 'c'orrcentric"therewith, said receptacle.having a smaller outside "diameter than the 'inside diameter of the third pipe leaving an annular space therebetween, struts connecting said receptacle "to said third pip'e, said receptacle having a dlose'dbottom, and'means'to. close thetop "of saidreceptacle, thelast said means having a hdle therethroug'h, (the top "of said receptacle telescoping snugly inside of the 'bOttOHlfdf said housing :against the second ring.

1. The 'comb'inationof claim 3 with. affiexible line connected at oneend to the :top iofsaid housingiand at the 'other end to the interior er one 'of'fsaid first 'and second pipes.

5. The'conibin'ation of-claim l'Withfa rod extending across 'the lower part 'of'saidfirst *p'ipe,.*a :swivl connected to said otherend :o'f'the flexible line, and airing connectedto said swivel 'and passed over said rod for sliding motion relativethereto. v p

-6. Apparatus for placingan'explosiveichargebeneath the 'earths "surface comprising a drill'pipe having. a water passage therethrough, a drill bit assembly 'havingha water passage therethrough, 'releasablvmeans "connecting said drill pipe to said drill bit assembly with their water passages in longitudinal alignment, said drill bit assembly having an explosive charge secured therein, a length of ignition cable within said water passages, said ignition cable beirrg -connected 'at-one end -to 'saidexplosive charge and at the other end to 's'aid drill *pipeyand "shielding means adapted-'to protect said ignition cable and 'said explosive charge from fiuid fiow through said 'water passages.

References Cited in the file of this patent UNITED STATES "PATENTS #145114 C-arlisle Oct/21,1952, 

